Barrier-coated stopper and method of forming the same

Abstract

A method for forming a molding device (e.g., a stop) requiring minimal post-molding processing includes: providing a four-plate mold assembly (52) having a top plate (54), a sprue / vent plate (56) including a core (62), a main plate (58) including a groove (66) defining a mold cavity (68) having a corrugated surface (70), and a bottom plate (60); closing the mold assembly (52) such that the core (62) enters the groove (66) in the main plate (58) to define a space (72) corresponding to the shape of the stop (10, 110) to be formed; introducing a polymer material into the mold cavity (68) to form the stop (10, 110); and inserting a barrier film (14, 114) between the main plate (58) and the bottom plate and attaching it to the formed stop (10, 110). Open the top plate, gate / vent plate, main plate and bottom plate, and remove the molded stop.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to U.S. Provisional Application No. 63 / 116,533, filed November 20, 2020, entitled “Barrier-Coated Stopper and Method of Forming Same,” the entire disclosure of which is incorporated herein by reference.

[0003] Background of the Invention

[0004] Field of the Invention

[0005] The present invention relates to a method for molding a device (e.g., a stop for use with a plunger rod in a syringe or a stop for sealing a bottle), and more specifically, to a method for molding a stop using a four-plate, one-shot injection molding device that requires minimal post-molding processing.

[0006] Description of related technologies

[0007] Syringe assemblies (particularly hypodermic syringes) are well-known in the medical field for dispensing fluids (e.g., drugs). Conventional syringes typically comprise an elongated barrel having opposing proximal and distal ends and a chamber located between these ends for containing fluid. A channel extends through the distal end of the syringe barrel and communicates with the chamber. The distal end of the syringe barrel is connected to a needle cannula for delivering fluid from the chamber and the channel. The proximal end of the syringe barrel slidably accommodates a plunger rod and a stop assembly, such that a force applied to the plunger rod causes the stop to move along the barrel, driving fluid from the chamber through the needle cannula.

[0008] Currently, a problem with some hypodermic syringes on the market is that, during injection, after the stop has been pushed the entire length of the syringe barrel, a certain amount of liquid may remain inside (i.e., "dead volume"). Therefore, there is a need to produce a stop that can reduce the amount of dead space within the syringe barrel. Various stops have been designed to reduce or minimize dead space within the syringe barrel and to adequately seal the inner wall of the syringe barrel. One example of a stop is disclosed in patent US 5795337, which is incorporated herein by reference in its entirety. This design includes a piston-shaped stop body for slidably achieving a liquid-tight connection within the syringe barrel. The body includes a distal end, a proximal end, and a longitudinal axis passing through the distal and proximal ends. A distally pointed conical projection is positioned on the distal end of the stop body. At least one elongated discontinuity extending along the conical projection is provided. This discontinuity serves to prevent an undesirable immediate seal of the stop protrusion within the channel extending from the syringe barrel to the needle cannula, allowing any trapped fluid within the barrel to flow along these discontinuities and into the channel. Because the stop is made of an elastic material, further pressure on the plunger rod in the distal direction will cause the stop to twist and squeeze the fluid through the channel, which remains temporarily open due to the discontinuity.

[0009] Stops with complex shapes featuring barrier membranes on their distal surfaces are typically formed using a two-step molding / trimming process. These types of stops are currently used only for low-volume production where cost is less of a concern. The cost of a two-step process is approximately twice that of a traditional single-step process. Some commercially available barrier-coated stops use a single-step molding process; however, these stops often have undesirable characteristics. One such undesirable characteristic is that the first rib must be a trimmed edge, not a molded feature, thus compromising fluid sealing and optimal sliding force. While the stop includes two additional ribs and addresses container closure integrity (CCI) risks, this design is undesirable for certain devices, such as precision syringes, where variable leakage through the first stop rib can affect drug dosing accuracy and system hysteresis. Some stop designs have overcome these limitations, but so far, they have only been produced in manufacturing processes requiring two complete molding and trimming steps. This production is not only costly, but the more steps in the process, the greater the potential for waste and scrap. Scaling up the production of these types of high-precision stops using a one-step molding process can bring significant economic advantages. Summary of the Invention

[0010] According to one aspect, this disclosure relates to a method for molding an apparatus (e.g., a stop) using a single-stage injection molding apparatus requiring minimal post-molding processing. The method includes the steps of: providing a four-plate mold assembly having a top plate, a sprue / vent plate including a core, a main plate including a recess defining a mold cavity having a corrugated profile surface, and a bottom plate; closing the mold assembly such that the core enters the recess in the main plate to define a space corresponding to the shape of the apparatus to be molded; and introducing a polymer material into the mold cavity to fill the mold cavity and the space, thereby forming the molded apparatus. The molded apparatus will have a body and a molding surface corresponding to the corrugated profile surface of the mold cavity. The method further includes: cooling the polymer material; separating the sprue / vent plate from the main plate to withdraw the core from the molded apparatus; subsequently separating the sprue / vent plate from the top plate; subsequently separating the bottom plate from the main plate; and finally removing the molded apparatus (e.g., a stop) from the main plate.

[0011] The step of separating the gate / vent plate from the main plate opens the vent and retracts the core from the molding device and the main plate. It is understood that the core can be designed to have several shapes based on the desired internal shape of the device (e.g., a stop). For example, the core can have a threaded design, a conical portion, straight sidewalls, etc., wherein the conical portion has an enlarged portion toward the intersection of the core and the gate / vent plate. When the top plate, gate / vent plate, main plate, and bottom plate of the mold assembly are opened, the molding device can be removed from the main plate by pulling it through the bottom of the main plate.

[0012] The steps of introducing polymer material into the mold cavity include: injecting hot polymer material into the mold cavity through an injection nozzle and runner associated with the top plate, and the steps of cooling the mold assembly include: providing cooling material to the main plate.

[0013] The corrugated surface of the main cavity is the shape of a stop having a body defining an open rear end, a closed front end, and a cylindrical sidewall extending between the open rear end and the closed front end. According to one embodiment, the corrugated surface is configured to create a plurality of ribs extending radially outward around the outer edge of the body and spaced axially along the body. It is understood that the mold cavity may have other corrugated surfaces to manufacture other products and / or create stops with different shapes.

[0014] According to one embodiment, the base plate may have a plane configured to create a stop having a flat surface at its distal end. According to another embodiment, the base plate may include a corrugated surface configured to create a stop having a distal end with a flat portion extending inwardly from the outer edge of the closed front or distal end of the stop, wherein the corrugated surface is shaped to create a protrusion extending from the closed front end, wherein the protrusion defines a base as it intersects the distal end of the stop and extends from the flat portion at the top of the closed front end, the protrusion being configured to engage within the syringe barrel to reduce dead zones during injection. It is understood that the base plate may have other designs to create stops with various shapes at their distal ends.

[0015] The method may further include the step of: disposing a membrane (e.g., a barrier membrane) between the base plate and the main plate, wherein the membrane is clamped between the base plate and the main plate when the mold assembly is closed, and is secured to the molding apparatus when removed from the mold assembly. It is understood that the barrier membrane may be a known membrane that provides a low-friction barrier between, for example, the stop and a pharmaceutical composition (e.g., a drug, pharmaceutical product, or other therapeutic material) in the syringe barrel, and can prevent material from leaching from the stop or prevent the stop from extracting the mixture from the pharmaceutical composition. The method also includes the step of trimming and removing excess membrane from the molding apparatus.

[0016] According to another aspect, this disclosure relates to a system for molding a device (e.g., a stop), the system comprising a mold assembly having a top plate, a gate / vent plate, a main plate, and a bottom plate. The gate / vent plate includes a core extending from its surface. It is understood that the core can have any shape based on the desired internal shape of the device (e.g., a stop) being molded. For example, the core can have a threaded design, a conical portion, straight sidewalls, etc., the conical portion having an enlarged portion toward the intersection of the core and the gate / vent plate. The main plate of the mold assembly includes a recess defining a mold cavity having a corrugated surface. This mold cavity is configured to receive the core from the gate / vent plate to define a space corresponding to the shape of the device to be molded. An injection nozzle and runner mate with the top plate. The injection nozzle and flow channel are configured to supply polymer material into the mold cavity to fill the space, thereby forming the molding apparatus having a body and a molding surface corresponding to the wavy profile surface. At least one cooling member is provided for cooling the polymer material within the mold cavity.

[0017] The system further includes: a first mechanism for separating the gate / vent plate from the main plate to retract the core from the molding apparatus; a second mechanism for separating the gate / vent plate from the top plate; and a third mechanism for separating the bottom plate from the main plate to allow removal of the core from the main plate into the molding apparatus. According to one embodiment, the first, second, and third mechanisms for separating the top plate, the gate / vent plate, the main plate, and the bottom plate of the mold assembly include a series of spring mechanisms or a series of core lifters with different forces to sequentially separate the gate / vent plate from the main plate, the gate / vent plate from the top plate, and the bottom plate from the main plate; wherein the spring mechanism includes guide pins for limiting the opening of each of the top plate, the gate / vent plate, the main plate, and the bottom plate.

[0018] According to one embodiment, a membrane can be inserted between the base plate and the main plate, such that the closure of the mold assembly clamps the membrane between the base plate and the main plate to secure the membrane to the forming device. The system may also include a trimming die for removing excess membrane from the forming device. According to one design, the trimming die may include a flat punch for removing excess membrane; however, it is understood that other types of molds with other types of cutting surfaces (e.g., sharp edges), and / or other types of trimming devices with or without airflow, may be used to remove the excess membrane.

[0019] According to another aspect, this disclosure relates to a stop adapted for attachment to a plunger rod for use within a syringe barrel. The stop includes a body defining an open rear end, a closed front end, and a cylindrical sidewall extending between the open rear end and the closed front end. The open rear end is adapted to receive a front end attachment portion of the plunger rod. The stop also includes at least one rib extending radially outward about an outer edge of the body. The at least one rib is configured to form an active seal with the syringe barrel. A flat portion is disposed on the top outer edge surface of the closed front end of the stop and adjacent to the at least one rib. The flat portion extends inward from the outer edge of the stop. The stop also includes a protrusion extending from the closed front end, wherein the protrusion defines a base as it intersects with a distal end of the stop and extends from the flat portion toward the top of the closed front end. The base diameter is smaller than the outer diameter of the distal end of the stop, and the protrusion has a profile configured to mate with the inner surface of the syringe barrel to reduce dead angles during injection.

[0020] Further examples of this disclosure will now be described in the following numbered entries.

[0021] Article 1: A method for molding an apparatus, comprising the following steps: providing a mold assembly having a top plate, a sprue / vent plate including a core, a main plate including a groove defining a mold cavity having a corrugated profile surface, and a bottom plate; closing the mold assembly such that the core enters the groove in the main plate to define a space corresponding to the shape of the apparatus; introducing a polymer material into the mold cavity to fill the mold cavity and the space, thereby forming a molded apparatus having a body and a molding surface corresponding to the corrugated profile surface; separating the sprue / vent plate from the main plate to withdraw the core from the molded apparatus; subsequently separating the sprue / vent plate from the top plate; subsequently separating the bottom plate from the main plate; and removing the molded apparatus from the main plate.

[0022] Article 2: According to the method described in Article 1, wherein the step of separating the gate / vent plate from the main plate causes the vent to open and the core to be withdrawn from the molding apparatus and the main plate.

[0023] Article 3: The method according to Article 1 or 2, wherein the step of removing the molding device from the motherboard includes: removing the molding device through the bottom of the motherboard.

[0024] Article 4: The method according to any one of Articles 1 to 3, wherein the step of introducing polymer material into the mold cavity comprises: injecting polymer material into the mold cavity through an injection nozzle and flow channel associated with the top plate.

[0025] Article 5: The method according to any one of Articles 1 to 4, wherein after the step of introducing the polymer material into the mold cavity, the mold assembly is heated to solidify the polymer material, or the mold assembly is cooled by supplying cooling material to the main board.

[0026] Article 6: The method according to any one of Articles 1 to 5, wherein the wavy outer surface of the main cavity is the shape of a stop having a body defining an open rear end, a closed front end, and a cylindrical sidewall extending between the open rear end and the closed front end.

[0027] Article 7: The method according to Article 6, wherein the shape of the wavy profile surface is configured to create a plurality of ribs that extend radially outward around the outer edge of the body and are axially spaced along the body.

[0028] Article 8: The method according to Article 6 or 7, wherein the base plate has a plane configured to create a stop having a plane, or the base plate includes a corrugated surface configured to create a stop having a flat portion located on the outer edge of the closed front end of the stop and extending inward from the outer edge of the stop, wherein the corrugated surface is shaped to create a protrusion extending from the closed front end, wherein the protrusion defines a base as it intersects the distal end of the stop and extends from the flat portion at the top of the closed front end, the protrusion being configured to engage within the syringe barrel to reduce dead zones during injection.

[0029] Article 9: The method according to any one of Articles 1 to 8 includes the step of placing a membrane between the base plate and the main plate, wherein when the mold assembly is closed, the membrane is clamped between the base plate and the main plate, and when the molding device is removed from the mold assembly, the membrane is fixed to the molding device.

[0030] Article 10: The method described in any one of Articles 1 to 9 includes the step of trimming excess film from the forming apparatus.

[0031] Article 11: A system for molding an apparatus, the system comprising: a mold assembly having a top plate, a gate / vent plate, a main plate, and a bottom plate, the gate / vent plate including a core extending from its surface, the main plate including a groove defining a mold cavity having a corrugated surface, the mold cavity being configured to receive the core from the gate / vent plate to define a space corresponding to the shape of the apparatus to be molded; an injection nozzle and runner engaging with the top plate, the injection nozzle and runner being configured to supply polymer material to the mold. The mold assembly comprises a cavity to fill the space, thereby forming the molding device, the molding device having a body and a molding surface corresponding to the wavy outer surface; at least one cooling member for cooling the polymer material within the mold cavity; a first mechanism for separating the gate / vent plate from the main plate to retract the core from the molding device; a second mechanism for separating the gate / vent plate from the top plate; and a third mechanism for separating the bottom plate from the main plate to allow removal of the molding device from the main plate.

[0032] Article 12: The system according to Article 11, wherein the first mechanism, the second mechanism, and the third mechanism for separating the top plate, the sprue / vent plate, the main plate, and the bottom plate of the mold assembly comprises a series of spring mechanisms or a series of core lifters with different forces to sequentially separate the sprue / vent plate from the main plate, the sprue / vent plate from the top plate, and the bottom plate from the main plate; wherein the spring mechanism includes guide pins for limiting the opening of each of the top plate, the sprue / vent plate, the main plate, and the bottom plate.

[0033] Article 13: The system according to Article 11 or 12, wherein the membrane can be inserted between the base plate and the main plate, wherein the closure of the mold assembly causes the membrane to be clamped between the base plate and the main plate, thereby fixing the membrane to the molding device.

[0034] Article 14: A system according to any one of Articles 11 to 13 includes a trimming die with a flat punch for removing excess film from the forming apparatus, wherein the trimming die optionally includes a central opening through which a clean airflow can move to remove the trimmed portion from the trimming die or die module.

[0035] Article 15: A stop member adapted for attachment to a plunger rod for use within a syringe barrel, the stop member comprising: a body defining an open rear end, a closed front end, and a cylindrical sidewall extending between the open rear end and the closed front end; a barrier membrane covering at least the closed front end of the body; the open rear end being adapted to receive a front attachment end of the plunger rod; at least one rib extending radially outward about an outer edge of the body, the at least one rib being configured to form an active seal with the syringe barrel; a flat portion. The flat portion is located on the top outer edge surface of the closed front end and adjacent to the at least one rib, the flat portion extending inward from the outer edge of the stop; and a protrusion extending from the closed front end, wherein, as the protrusion intersects the closed front end of the stop and extends from the flat portion toward the top of the closed front end, the protrusion defines a base, the base diameter of which is smaller than the outer diameter of the distal end of the stop, and the protrusion has a profile configured to mate with the inner surface of the syringe barrel to reduce dead angles during injection.

[0036] Article 16: The stop as described in Article 15, wherein the flat portion is approximately 0.75 mm to 1 mm wide, extending up to the starting point of the upward slope forming the protrusion.

[0037] Article 17: A stop member according to Article 15 or 16, wherein the at least one rib includes a first rib, a second rib, and a third rib, wherein the diameter of the second rib is smaller than the diameters of the first rib and the third rib.

[0038] Article 18: A stop member according to any one of Articles 15 to 17, wherein the open rear end of the stop member includes a cavity configured to receive the front attachment end of the plunger rod, wherein the inner surface of the cavity includes a plunger rod cavity protrusion extending from the bottom surface of the closed front end of the stop member.

[0039] Article 19: The stop according to Article 18, wherein the plunger rod cavity protrusion is configured to engage slightly with the front attachment end of the plunger rod to increase the force transmitted to the front side of the stop, wherein the plunger rod cavity protrusion has inclined sidewalls.

[0040] Article 20: A stop member according to any one of Articles 15 to 19, wherein the open rear end of the stop member includes a cavity having a series of threads for threaded attachment to the attachment end of the plunger rod, wherein the threads have a pitch that decreases slightly toward the bottom of the plunger rod cavity.

[0041] Article 21: The stop member according to any one of Articles 15 to 20, wherein the thickness between the top profile spline AA-BB and the inner top protrusion LL decreases monotonically and protrudes upward to point XX.

[0042] Article 22: The stop member as described in Article 21, wherein point XX is within the range of 0.25mm-0.75mm of the wall thickness of the stop member as defined by YY. Attached Figure Description

[0043] The above and other features and advantages of this disclosure, as well as the ways in which they are implemented, will become more apparent from the following description of embodiments of this disclosure taken in conjunction with the accompanying drawings, in which:

[0044] Figure 1A This is a top perspective view of a stop member used in a syringe according to an embodiment of the present invention.

[0045] Figure 1B This is an embodiment of the present invention. Figure 1A A side perspective view of the stop component.

[0046] Figure 2A This is a top perspective view of a stop member used in a syringe according to an embodiment of the present invention.

[0047] Figure 2B This is an embodiment of the present invention. Figure 2A A sectional side view of the stop component.

[0048] Figure 3This is a cross-sectional side view of a four-plate, one-stage injection molding apparatus (also referred to as a mold) according to an embodiment of the present invention. This four-plate, one-stage injection molding apparatus can be used to form a molding device, for example... Figures 1A to 1B and Figures 2A to 2B Stopping components.

[0049] Figure 4 This is an embodiment of the present invention. Figure 3 A perspective view of the mold in the open state, including the removal of the molded stop.

[0050] Figures 5A to 5E The use according to an embodiment of the present invention is shown. Figure 3 The mold is used to form the device in a specific sequence of steps.

[0051] Figure 6A It is used in accordance with embodiments of the present invention for... Figures 1A to 1B A side perspective view of the die punch used to cut off excess barrier film after the stop component is formed.

[0052] Figure 6B This is an embodiment of the present invention. Figure 6A A side perspective view of a die punch, including an air duct for removing excess film.

[0053] Figure 7A This is an embodiment of the present invention. Figures 1A to 1B Side view of the stop component.

[0054] Figure 7B According to an embodiment of the present invention, along Figure 7A The sectional view of the stop element taken from line 7B-7B.

[0055] Figure 7C This is an embodiment of the present invention. Figure 7A Top view of the stop component.

[0056] Figure 7D This is an embodiment of the present invention. Figure 7A A bottom view of the stop component.

[0057] Figure 7E This is an embodiment of the present invention. Figure 7A A side view of the stop, wherein a portion of the stop is cut off to show the interaction between the plunger rod core and the inner portion of the distal end of the stop.

[0058] Figure 7F This is an embodiment of the present invention. Figure 7A A partial sectional perspective view of the stop, showing the internal thread and internal portion at the distal end of the stop.

[0059] Figure 7G This is an embodiment of the present invention. Figure 7A A cross-sectional view of the stop, showing that the pitch of the internal thread of the stop increases toward the bottom of the plunger rod cavity.

[0060] Figure 8 This is a cross-sectional view of a stop member fixed to the attachment end of a plunger rod according to an embodiment of the present invention, the stop member being... Figure 3 It is formed by the molding device.

[0061] Figure 9A and Figure 9B The diagram illustrates the assembly of the syringe barrel before and after applying a distal force to the plunger rod and stop, according to an embodiment of the invention. Figure 8 The design of the stop component.

[0062] Figure 10A This illustrates the use according to an embodiment of the invention. Figures 1A to 1B The stop design is a representative view of the amount of dead angle generated inside the syringe barrel after a force is applied to the plunger rod in a distal direction.

[0063] Figure 10B This illustrates the use according to an embodiment of the present invention. Figures 2A to 2B The stop design represents the amount of dead angle generated inside the syringe barrel after a force is applied to the plunger rod pointing distally.

[0064] Figure 11 This is a perspective sectional view of the stop member according to an embodiment of the present invention.

[0065] In all views of a plurality of views, corresponding reference numerals refer to corresponding parts. The examples presented herein illustrate exemplary embodiments of this disclosure, and such examples should not be construed as limiting the scope of this disclosure in any way. Detailed Implementation

[0066] The following description is provided to enable those skilled in the art to make and use the described embodiments intended for carrying out the invention. However, various modifications, equivalents, variations, and substitutions will still be apparent to those skilled in the art. Any and all such modifications, variations, equivalents, and substitutions are intended to fall within the spirit and scope of the invention.

[0067] In the following text, for descriptive purposes, the terms “up,” “down,” “right,” “left,” “vertical,” “horizontal,” “top,” “bottom,” “lateral,” “longitudinal,” and their derivatives will be used in relation to the concept as oriented as shown in the accompanying drawings. However, it should be understood that the concept can be adapted in various alternative variations unless explicitly stated otherwise. It should also be understood that the specific devices shown in the accompanying drawings and described in the following specification are merely exemplary embodiments of the concept. Therefore, the specific dimensions and other physical characteristics associated with the embodiments disclosed herein should not be considered limiting.

[0068] Furthermore, for the purposes of describing the present invention, the term "distal" refers to the end of the syringe needle that protrudes from the syringe and the end of the stop member that is closer to the syringe needle, while the term "proximal" refers to the end of the syringe that is closer to the syringe holder and furthest from the needle tip, and the end of the stop member that is furthest from the needle tip.

[0069] Now for reference Figures 1A to 1B and Figures 2A to 2B , Figures 1A to 1B and Figures 2A to 2B Two different types of stop members 10 and 110 are shown, which can be used with the present disclosure. Figure 3 and Figure 4 The four-plate, one-stage injection molding system (generally referred to as 50) is used for production. The stop may include multiple annular ribs 12, 112, which are configured to seal against the inner surface of the syringe barrel 16 using a liquid-tight engagement, such as... Figures 9A to 9B As shown.

[0070] like Figure 9A and Figure 9B As shown, a syringe barrel typically includes an open proximal end, a distal end 38, and a cylindrical body portion that defines a chamber for retaining liquid (e.g., a liquid drug) between the proximal and distal ends. The syringe barrel may be made of glass, plastic, or a combination thereof, and may include a flange at its proximal end. Examples of plastic materials that can be used to form the syringe barrel include, but are not limited to, substantially transparent thermoplastic materials, such as polycarbonate, polypropylene, polyethylene terephthalate (PET), etc.

[0071] Stop 10 can be positioned within the syringe barrel and fluid-tightly engaged with it by the action of annular rib 12, and stop 110 can be positioned within the syringe barrel and fluid-tightly engaged with it by the action of annular rib 112, wherein the distal end 20 of stop 10 and the distal end 120 of stop 110 face the distal end of the syringe barrel. The distal end 38 of the syringe barrel includes a channel 39 that is in fluid communication with a chamber. An elongated needle cannula (not shown) having a lumen extending therethrough can be provided to be attached to the distal end 38 of the barrel, such that the lumen is in fluid communication with the chamber through the channel. It is understood that the needle can be permanently attached to the syringe barrel (e.g., by using an adhesive), or the needle can be removably attached to the syringe barrel (e.g., by a needle hub that is permanently attached to the needle cannula and frictionally attached to the distal end of the syringe barrel). Stops 10 and 110 will be able to slide within the chamber for initial positioning near the drug and subsequently facilitate drug passage through the lumen of the needle cannula or through the channel of the distal end 38 of the syringe barrel. Alternatively, for restoration purposes, stops 10 and 110 can slide inside the syringe barrel.

[0072] Barrier membrane 14 can be disposed on the distal end 20 of the stop member, and barrier membrane 114 can be disposed on the distal end 120 of the stop member to reduce and / or eliminate direct contact between the material of the stop members 10 and 110 and the contents of the syringe, and to reduce friction between the contents of the syringe and the stop members 10 and 110.

[0073] Continue to refer to Figure 3 and Figure 4 , Figure 3 and Figure 4A four-plate injection molding system 50 is shown. Although the molding system relates to molding a stop for use with a syringe plunger rod, it is understood that the molding system can be used to mold other products, such as seals for medical vials or test tubes, or other known molding devices. The molding system 50 includes a mold assembly 52 having a top plate 54, a sprue / vent plate 56, a main plate 58, and a bottom plate 60. The sprue / vent plate 56 includes a core 62 extending from its bottom surface 64. It is understood that the core 62 can have any shape based on the desired internal shape of the device being molded (e.g., stops 10, 110). For example, the core 62 can have a threaded design, a conical portion, straight sidewalls, etc., the conical portion having an enlarged portion toward the intersection of the core and the sprue / vent plate. The main plate 58 of the mold assembly includes a recess 66 that defines a mold cavity 68 having a wavy profile surface 70. The mold cavity 68 is configured to receive the core 62 from the gate / vent plate 56, defining a space 72 corresponding to the shape of the device to be molded. An injection nozzle 74 and a runner 76 mate with a top plate 54. The injection nozzle 74 and the runner 76 are configured to supply polymer material into the mold cavity 68 to fill the space 72, forming a molding device having a body and a molding surface corresponding to the corrugated profile surface 70. At least one cooling member 78 is provided for cooling the polymer material within the mold cavity 68. The cooling member 78 may be a series of pipes including a cooling medium flowing therein or any other known cooling member.

[0074] System 50 also includes a first mechanism 80, a second mechanism 81, and a third mechanism 82. The first mechanism separates the gate / vent plate 56 from the main plate 58 to retract the core 62 from the molding apparatus (e.g., stops 10, 110); the second mechanism separates the gate / vent plate 56 from the top plate 54; and the third mechanism separates the bottom plate 60 from the main plate 58 to allow the molding apparatus (e.g., stops 10, 110) to be removed from the main plate 58. According to one embodiment, the first mechanism 80, the second mechanism 81, and the third mechanism 82 for separating the top plate, the gate / vent plate, the main plate, and the bottom plate of the mold assembly include a series of spring mechanisms with different forces to sequentially separate the gate / vent plate 56 from the main plate 58, the gate / vent plate 56 from the top plate 54, and the bottom plate 60 from the main plate 58. These spring mechanisms may include guide pins to limit the opening of each plate. It is also understood that the first mechanism 80, the second mechanism 81, and the third mechanism 82 used to separate the top plate, gate / vent plate, main plate, and bottom plate of the mold assembly may include a series of core lifters.

[0075] According to one embodiment, barrier films 14, 114 can be inserted between the base plate 60 and the main plate 58, such that the closure of the mold assembly 52 clamps the films 14, 114 between the base plate 60 and the main plate 58, thereby securing the films 14, 114 to the molded stops 10, 110. Using the barrier films 14, 114 on the stops improves the sliding motion of the stops within the syringe barrel. The barrier films 14, 114 should not exhibit adverse effects on the drug and should not contain silicone-based materials (e.g., silicone oil). An example of barrier films 14, 114 that can be used is a fluoropolymer laminate, known for its good biocompatibility, good mechanical integrity, inertness, and processability. The excellent strength of the expanded fluoropolymer structure allows these materials to form thin barriers that remain intact during the molding process and during the installation of the stops into the syringe barrel. For example, the barrier membrane can be selected from the group consisting of polytetrafluoroethylene (PTFE) resin, ethylene tetrafluoroethylene copolymer (ETFE) resin, expanded polytetrafluoroethylene (ePTFE), etc. Figure 6A and Figure 6B As shown, a trim die 84, which is further discussed in detail below, can be provided to remove excess barrier membranes 14, 114 from the forming device.

[0076] Now for reference Figures 5A to 5E , Figures 5A to 5E The sequential steps for molding a device (e.g., stops 10, 110) using the four-platen injection molding system 50 of the present invention are shown. Reference Figure 5A The method includes: providing a four-plate mold assembly 52 having a top plate 54, a gate / vent plate 56 including a core 62, a main plate 58 including a recess defining a mold cavity 68 having a corrugated profile surface 70, and a bottom plate 60; closing the mold assembly 52 such that the core 62 enters the recess 66 in the main plate 58 to define a mold cavity 68 having a corrugated profile surface 70. Figure 3 The mold assembly 52 includes a space 72 corresponding to the shape of the device to be molded (e.g., stops 10, 110); and a space 72 for introducing polymer material into the mold cavity 68 to fill the mold cavity 68 and the space, thereby forming the molding device (e.g., stops 10, 110). The mold assembly 52 may include an optional component 53, which includes a pin-shaped member (not shown) that can be held by hand by an operator to push multiple parts out of the main board 58.

[0077] The molding apparatus will have bodies 18, 118 and a molding outer surface corresponding to the corrugated outer surface 70 of the mold cavity 68. Depending on the type of polymer material used, for example, in the case of using a thermoplastic elastomer, the method may include a step of cooling the polymer material. If the polymer material comprises uncured rubber, the mold is heated (e.g., to approximately 180°C) after the material is introduced into the mold cavity to cure the rubber. After cooling the polymer material or heating the rubber for curing, as... Figure 5B As shown, the gate / vent plate 56 is separated from the main plate 58 to retract the core 62 from the mold cavity 68, the recess 66, and the molding apparatus (e.g., stops 10, 110). Next, as... Figure 5C As shown, separate the gate / vent plate 56 from the top plate 54. Then, as... Figure 5D As shown, separate the base plate 60 from the main plate 58. Then, as... Figure 5E As shown, for example, the molding device (e.g., stop members 10, 110) can be removed from the bottom 59 of the main board 58.

[0078] like Figure 4 As shown, the step of separating the gate / vent plate 56 from the main plate 58 causes the vent 57 to open and allows the core 62 to be retracted from the molding device (e.g., stops 10, 110) and the main plate 58. It is understood that the core 62 can be designed to have several shapes based on the desired internal shape of the device (e.g., stops 10, 110). For example, the core can have a threaded design, a conical portion, straight sidewalls, etc., wherein the conical portion has an enlarged portion toward the intersection of the core and the gate / vent plate. When the plate of the mold assembly 52 is opened, the molding device (e.g., stops 10, 110) can be removed from the main plate 58 by pulling the molding device through the bottom 59 of the main plate 58.

[0079] Return to reference Figure 3The step of introducing the polymer material into the mold cavity includes injecting the polymer material into the mold cavity 68 through the injection nozzle 74 and runner 76 associated with the top plate 54. The polymer material may be synthetic rubber; however, it is understood that other materials, such as natural rubber, elastomers, and combinations thereof, may also be used. Examples of elastomers that can be used as polymer materials include, but are not limited to, silicone rubber, natural rubber, styrene-butadiene rubber (SBR), ethylene-propylene diene monomer (EPDM), neoprene rubber, etc. If the polymer material contains an elastomer, the material is heated, depending on the material, but typically to about 225°C. Alternatively, if the material includes, for example, a thermosetting rubber, the material is only heated to its melting point temperature (i.e., about 20°C–50°C) so that it can be injected into the mold cavity. If necessary, the step of cooling the mold assembly includes supplying a cooling medium to the main plate 58 (e.g., via cooling member 78).

[0080] Return to reference Figures 1A to 1B and Figures 2A to 2B The corrugated surface of the mold cavity can be the shape of stop 10 (having a body 18 defining an open rear end 22, a closed front or distal end 20, and a cylindrical sidewall 24 extending between the open rear end 22 and the closed front or distal end 20) or stop 110 (having a body 118 defining an open rear end 122, a closed front or distal end 120, and a cylindrical sidewall 124 extending between the open rear end 122 and the closed front or distal end 120). According to one embodiment, the shape of the corrugated surface is configured to create a plurality of annular ribs 12, 112 extending radially outward around the outer edge of the bodies 18, 118 and axially spaced along the bodies 18, 118. It is understood that the mold cavity can have other corrugated surfaces to manufacture other products and / or create stops 10, 110 with different shapes.

[0081] According to one embodiment, the base plate 60 may have a flat face configured to create a stop 110 having a flat face 121 at its distal end 120, such as Figure 2A and 2B As shown. According to another embodiment, the base plate 60 may include a corrugated surface configured to create a stop 10 having a distal end 20, such as... Figure 1A and Figure 1B As shown below. Figures 7A to 7G The description elaborates on this in more detail. Figure 1A and Figure 1BThe overall shape of the stop. However, the base plate 60 has a corrugated surface configured to produce a stop having a distal end 20 and a protrusion 30, the distal end being in the shape of a flat portion 26 on the outer edge 28 of the closed front end or distal end 20 of the stop 10, the flat portion extending inward from the outer edge 28 of the stop 10, the protrusion extending from the closed front end or distal end 20, wherein, as the protrusion intersects the closed front end or distal end 20 of the stop and the protrusion includes an inclined portion (also referred to as an upward ramp) 34, the protrusion 30 defines a base 32: the inclined portion extending upward from the flat portion 26 at the top of the closed front end or distal end 20 toward the protrusion 30. The following is about... Figure 7B The inclined portion 34 is discussed in more detail. This protrusion is configured to engage within the syringe barrel 16 to reduce dead zones during injection. Understandably, the base plate 60 can have other designs to create stops of various shapes at its distal end.

[0082] The method may further include the following steps: disposing a membrane (e.g., barrier membranes 14, 114) between the base plate 60 and the main plate 58, wherein the membranes 14, 114 are clamped between the base plate 60 and the main plate 58 when the mold assembly 52 is closed, and the membranes 14, 114 are secured to the molding apparatus when the mold assembly 52 is removed from the molding apparatus. It is understood that the barrier membranes 14, 114 may be known membranes that provide a low-friction barrier between, for example, the stops 10, 110 and the pharmaceutical composition (e.g., a drug, pharmaceutical product, or other therapeutic material) in the syringe barrel 16, and can prevent material from leaching from the stops 10, 110 or prevent the stops 10, 110 from extracting the mixture from the pharmaceutical composition.

[0083] refer to Figure 6A and Figure 6BThe method also includes the step of trimming and removing excess film 14, 114 from the forming device (e.g., stops 10, 110). This trimming step can be performed using a trimming die 84. According to one design, the trimming die may include a flat punch 86 for removing excess film 14, 114. The trimming die 84 includes a punch center having an opening 88 extending therethrough, through which a clean airflow can move to remove the trimmed portion from the die module 85. The flat punch 86 has a flat surface 87 for removing excess film 14, 114. The central portion 90 in the punch 86 is deep enough to allow for multiple regrinding, which is more cost-effective than using a die punch with a razor edge (used when the stop does not have a flat portion but has a conical bevel starting from the edge and top rib of the stop). Sharp edges wear out quickly and require individual regrinding of the punch, which can be prohibitively expensive. However, it is understood that other types of molds with other types of cutting surfaces (e.g., sharp edges) and / or other types of trimming devices can be used to remove excess film.

[0084] Continue to refer to Figure 1A and Figure 1B And further reference Figures 7A to 7G , Figures 7A to 7G A type of stop 10 is shown, which can be manufactured using the injection molding system 50 of this disclosure. The stop 10 is adapted to be attached to the attachment end 17 of a plunger rod for use within a syringe barrel 16, such as... Figures 9A to 9B As shown.

[0085] As discussed above, the stop 10 includes a body 18 that defines an open rear end 22, a closed front or distal end 20, and a cylindrical sidewall 24 extending between the open rear end and the closed front or distal end 20. Barrier membrane 14 ( Figures 7A to 7G (Not shown) may be positioned at least adjacent to the closed front or distal end 20. The open rear end 22 is adapted to receive the front attachment portion (also referred to as the front attachment end, attachment end) 17 of the front side of the plunger rod. The stop 10 also includes at least one rib 12 extending radially outward around the outer edge of the body. The at least one rib 12 is configured to form an active seal with the syringe barrel 16. The annular or circumferentially extending rib 12 is intended to provide a stable liquid-tight seal between the stop body and the syringe barrel. It is understood that one or more ribs may be provided. Figures 7A to 7G In the disclosed embodiments, the body 18 may include a first rib 12a, a second rib 12b, and a third rib 12c, which extend radially outward around the outer edge of the body and are axially spaced along the body 18.

[0086] Rib 12 includes a recess 13 located therebetween, wherein the outer diameter of rib 12 is larger than the outer diameter of recess 13. Rib 12 may be curved when viewed from the distal end of stop body 10. It is understood that other embodiments of the stop (including those with smooth cylindrical side surfaces) may be formed using the molding system 50 of this disclosure.

[0087] The open rear end 22 of the stop 10 includes a cavity 35 configured to receive the front attachment end 17 of the plunger rod. According to... Figures 7A to 7G In the illustrated embodiment, the cavity 35 includes a thread 36 configured to mate with a thread 17a on the front attachment end 17 of the plunger rod, as shown. Figure 9A and Figure 9B As shown. It is understood that many methods exist for engaging the plunger rod with the stops 10, 110, and this threaded arrangement is an example of many possibilities. For example, the cavity 35 in the stop 10 may have a reduced diameter or neck at the proximal end of the cavity 35 and / or at the open rear end 22 of the stop 10. According to one arrangement, this cavity 35 may be shaped to receive an end or protrusion on the distal end or front attachment end 17 of the plunger rod, which has an enlarged distal end such that these portions will be assembled together in a snap-fit ​​arrangement. According to another example, the stop 10 may be bonded or co-formed to the attachment end 17 of the plunger rod.

[0088] Continue to refer to Figures 7A to 7G A flat portion 26 is disposed on the top outer edge surface of the closed front or distal end 20 of the stop 10, adjacent to at least one rib 12. The flat portion 26 extends inward from the outer edge 28 of the stop 10. According to one embodiment, the flat portion 26 may be approximately 0.75 mm to 1 mm wide, extending to the starting point of the upward ramp 34 forming the conical protrusion 30, wherein the apex of the conical protrusion is located at the top of the closed front or distal end 20 of the stop 10. As the protrusion intersects the closed front or distal end 20 of the stop 10 and extends from the flat portion 26 toward the top of the closed front or distal end 20, the protrusion 30 defines a base 32. The base diameter “BD” of the base 32 is smaller than the outer diameter “OD” of the closed front or distal end 20 of the stop 10, and the protrusion 30 has a profile configured to mate with the inner surface 40 of the syringe barrel, such as... Figure 9A and Figure 9B As shown, this is to reduce blind spots during injection.

[0089] Special Reference Figure 7B , Figure 7E and Figure 7FThe stop 10 of this disclosure can be designed such that the diameter of the second rib 12b is slightly smaller (up to 4%-15%) than the diameters of the other ribs 12a and 12c, to reduce the sliding force of the stop while still maintaining a seal. Based on the diameter of the cylinder, the rib radius of the second rib 12b at its apex can be approximately 0.45mm-0.65mm, resulting in a smaller sliding force. A plunger rod cavity protrusion 42 can be provided in the bottom of the cavity 35 of the stop 10. This cavity protrusion 42 is designed to engage slightly with the front attachment end 17 of the plunger rod, but rapidly increase the force transmitted to the front of the stop (compared to axial load transmitted via threads) to pull the first rib 12a first, making it easier (reducing the initial release force) to pull the stop 10 out. The sidewall 42a of the protrusion 42 is angled very steeply, for example, at approximately 60 degrees to the vertical line extending through the end of the stop 10, to make slight initial contact with the front attachment end 17 of the plunger rod, but the force increases rapidly. (Continue to refer to...) Figure 7B The thickness between the roof profile spline AA-BB and the inner top protrusion LL can be monotonically decreasing and bulging upwards to point XX. Point XX can be located between 0.25mm and 0.75mm within the thickness of the stop wall defined by YY. This particular design avoids bending of the top in the downward direction at locations with thinner cross-sections of the stop, and also prevents possible wrinkling of the barrier membrane 14.

[0090] like Figure 7G As shown, the pitch of the threads in the stop can be variable and non-constant, such that the pitch decreases toward the rear end or proximal side 22 of the stop and / or toward the bottom of the plunger rod cavity 35. This initially applies additional pressure to the front of the stop 10 to disengage the first rib 12a of the stop through a concentrated thumb force applied by the plunger rod. This also causes each stop rib to sequentially disengage from the container wall by pulling on its pusher rather than acting on the rear end or proximal side 22 of the stop 10. For example, as Figure 7G As shown, the length of the first pitch L1 can be shorter than the length of the second pitch L2. According to one example, the pitch from L2 to L1 can range from 2.1 mm to 1.4 mm. For instance, the pitch from L2 to L1 can be reduced by approximately two turns, where L2 is approximately 1.73 mm and L1 is approximately 1.57 mm.

[0091] Figure 8 A stop 10 is shown attached to the attachment end 17 of the plunger rod, which can be created using the four-plate injection molding system 50 of the present invention. It will be understood that this stop 10 may be formed with barrier films 14, 114, or without a barrier film. Figure 9A and Figure 9B It shows Figure 8The stop is designed to interact within the syringe barrel 16 after assembly and after 10 lbf (pound force) or 44.5 N is applied to the plunger rod. Figure 8 The design of the stop components and Figures 7A to 7G The design of the stop component 10 is similar. For example... Figure 9B As shown, after 10 lbf (44.5 N) is applied to the plunger rod, these stops minimize the amount of dead space within the syringe barrel 16.

[0092] refer to Figure 10A and Figure 10B It has been discovered that, with Figure 10B Compared to the stop 110, which has a flat or flat-headed 121 at its distal end 120, Figure 10A The stop 10 has a conical head or conical protrusion 30 at its distal end 20, which significantly reduces the dead zone at the injection tip. Dead zones cause the drug or medication to become trapped between the distal end 20 of the stop 10 and the inner surface 40 at the distal end of the syringe barrel 16, and between the distal end 120 of the stop 110 and the inner surface 140 at the distal end of the syringe barrel 116. The trapped drug or medication is commonly referred to as dead volume. Figure 10A The middle is represented by 41, in Figure 10B The dead volume 41, 141, remains in the syringe at the end of the injection and cannot be injected again regardless of the force applied to the plunger rod at the end of the injection. Figures 2A to 2B and Figure 10B As shown, the flat-head stop 110 is typically used with pre-fillable syringes ranging in size from 1ml to 3ml. However, finite element analysis (FEA) was performed to... Figures 1A to 1B and Figure 10A The dead volume of the conical head stop 10 is 41 and Figures 2A to 2B and Figure 10B The dead volume 141 of the flat-head stop 110 is compared. The results of this analysis are shown in Table 1 below. Typical forces applied to the stop are typically between 10 N and 25 N; however, Table 1 also shows values ​​above (44.5 N) and below (8.9 N) of this typical range.

[0093] Table 1

[0094]

[0095] As can be seen from Table 1, the dead volume 41 of the stop 10 of the conical head is approximately 4.5 mm. 3 It is significantly smaller than the dead volume of the flat-headed stop 110, wherein the dead volume 141 of the flat-headed stop is approximately 11.5 mm. 3 Up to 18.2mm3 .

[0096] Now for reference Figure 11 , Figure 11 A stop design is shown, including a fourth rib 12d disposed at the base 23 of the stop 10. This design includes a... Figures 7A to 7G The design features a thicker front section 46. This thicker front section 46 helps reduce bending of the stop 10. This special design, along with... Figures 7A to 7G The design is similar, including a distal end 20 and a protrusion 30. The distal end is shaped as a flat portion 26 on the outer edge 28 of the closed front end or distal end 20 of the stop 10. This flat portion extends inward from the outer edge 28 of the stop 10. The protrusion extends from the closed front end or distal end 20, wherein, as the protrusion intersects the closed front end or distal end 20 of the stop and includes an inclined portion 34, the protrusion 30 defines a base 32. This inclined portion extends upward from the flat portion 26 at the top of the closed front end or distal end 20 toward the protrusion 30. (See above regarding...) Figure 10A As discussed, the protrusion 30 is configured to fit within the syringe barrel 16 to reduce dead zones during injection.

[0097] While this disclosure has been described as having an exemplary design, further modifications can be made to this disclosure within its spirit and scope. Therefore, this application is intended to cover any variations, uses, or modifications of this disclosure using the general principles thereof. Furthermore, this application is intended to cover any deviations from this disclosure that are known or customary practices in the art to which this disclosure pertains and fall within the limitations of the appended claims.

Claims

1. A method for molding a device, comprising the following steps: A mold assembly is provided, the mold assembly having a top plate, a gate / vent plate including a core, a main plate including a groove defining a mold cavity having a corrugated surface, and a bottom plate; Close the mold assembly so that the core enters the groove in the motherboard to define a space corresponding to the shape of the device; A polymer material is introduced into the mold cavity to fill the mold cavity and the space, thereby forming a molding device having a body and a molding surface corresponding to the wavy outer surface. Separate the gate / vent plate from the main plate to remove the core from the molding apparatus; The gate / vent plate is then separated from the top plate; The base plate is then separated from the motherboard; as well as Remove the molding device from the motherboard.

2. The method according to claim 1, wherein, The step of separating the gate / vent plate from the main board opens the vent and removes the core from the molding apparatus and the main board.

3. The method according to claim 1, wherein, The step of removing the molding device from the motherboard includes: removing the molding device through the bottom of the motherboard.

4. The method according to claim 1, wherein, The step of introducing the polymer material into the mold cavity includes injecting the polymer material into the mold cavity through an injection nozzle and flow channel associated with the top plate.

5. The method according to claim 1, wherein, After the step of introducing the polymer material into the mold cavity, the mold assembly is heated to solidify the polymer material, or the mold assembly is cooled by supplying cooling material to the main board.

6. The method according to claim 1, wherein, The wavy outer surface of the mold cavity is the shape of a stop, which has a body that defines an open rear end, a closed front end, and a cylindrical sidewall extending between the open rear end and the closed front end.

7. The method according to claim 6, wherein, The shape of the wavy outer surface is configured to create a plurality of ribs that extend radially outward around the outer edge of the body and are axially spaced along the body.

8. The method according to claim 6, wherein, The base plate has a plane configured to create a stop with a planar surface, or the base plate includes a corrugated surface configured to create a stop having a flat portion located on the outer edge of a closed front end of the stop and extending inwardly from the outer edge of the stop, wherein the corrugated surface is shaped to create a protrusion extending from the closed front end, wherein the protrusion defines a base as it intersects the distal end of the stop and extends from the flat portion at the top of the closed front end, the protrusion being configured to engage within the syringe barrel to reduce dead zones during injection.

9. The method according to claim 1, further comprising the step of distributing a membrane between the base plate and the main plate, wherein, When the mold assembly is closed, the membrane is clamped between the base plate and the main plate, and when the molding device is removed from the mold assembly, the membrane is fixed to the molding device.

10. The method of claim 9, further comprising the step of trimming excess film from the forming apparatus.

11. A system for shaping an apparatus, comprising: A mold assembly having a top plate, a gate / vent plate, a main plate, and a bottom plate, the gate / vent plate including a core extending from a surface of the gate / vent plate, the main plate including a groove defining a mold cavity having a corrugated surface, the mold cavity being configured to receive the core from the gate / vent plate to define a space corresponding to the shape of the device to be formed; An injection nozzle and flow channel, which mate with the top plate, are configured to supply polymer material into the mold cavity to fill the space, thereby forming a molding device having a body and a molding surface corresponding to the wavy profile surface. At least one cooling component, the at least one cooling component being used to cool the polymer material within the mold cavity; A first mechanism is used to separate the gate / vent plate from the main plate to retract the core from the molding apparatus; A second mechanism is used to separate the gate / vent plate from the top plate; as well as A third mechanism is used to separate the base plate from the main plate so that the molding device can be removed from the main plate.

12. The system according to claim 11, wherein, The first, second, and third mechanisms for separating the top plate, the gate / vent plate, the main plate, and the bottom plate of the mold assembly include a series of spring mechanisms or a series of core lifters with different forces to sequentially separate the gate / vent plate from the main plate, the gate / vent plate from the top plate, and the bottom plate from the main plate; wherein the spring mechanism includes a guide pin for limiting the opening of each of the top plate, the gate / vent plate, the main plate, and the bottom plate.

13. The system according to claim 11, wherein, A membrane can be inserted between the base plate and the main plate, wherein the closure of the mold assembly causes the membrane to be clamped between the base plate and the main plate, thereby fixing the membrane to the molding device.

14. The system of claim 13, further comprising a trimming die having a flat punch for removing excess film from the forming apparatus.

15. A stop formed by the method according to any one of claims 1 to 10 or produced by the system according to any one of claims 11 to 14, the stop being adapted to be attached to a plunger rod for use within a syringe barrel, the stop comprising: The body defines an open rear end, a closed front end, and a cylindrical sidewall extending between the open rear end and the closed front end, the open rear end being adapted to receive an attachment end of the front side of the plunger rod. A barrier membrane, wherein the barrier membrane is positioned adjacent to the closed front end; At least one rib extends radially outward around the outer edge of the body, and the at least one rib is configured to form an active seal with the syringe barrel; A flat portion, the flat portion being located on the top outer edge surface of the closed front end and adjacent to the at least one rib, the flat portion extending inward from the outer edge of the stop; as well as A protrusion extending from the closed front end, wherein, as the protrusion intersects the closed front end of the stop and extends from the flat portion toward the top of the closed front end, the protrusion defines a base having a base diameter smaller than the outer diameter of the distal end of the stop, and the protrusion having a profile configured to mate with the inner surface of the syringe barrel to reduce dead angles during injection.

16. The stop member according to claim 15, wherein, The thickness between the top profile spline AA-BB and the inner top protrusion LL is monotonically decreasing and protrudes upward to point XX.

17. The stop member according to claim 15, wherein, Point XX is within the range of 0.25mm - 0.75mm of the thickness of the stop wall defined by YY.

18. The stop member according to claim 15, wherein, The open rear end of the stop includes a cavity having a series of threads for threaded attachment to the attachment end of the plunger rod, wherein the threads have a pitch that increases toward the bottom of the plunger rod cavity.

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